Foam well cleanout using oligomeric sulfonic acids

ABSTRACT

Organic disulfonic acids are produced by heating a sulfonate monomer at a temperature above 110°C. in the substantial absence of water. Olefin sulfonation product mixtures, hydroxyalkane sulfonic acids, alkane sultones, alkene sulfonic acids and mixtures thereof are oligomerized under these conditions.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of application Ser. No. 276,265,filed July 28, 1972, now abandoned, which, in turn, is a division ofapplication Ser. No. 858,097, filed Sept. 15, 1969, now U.S. Pat. No.3,721,707 issued Mar. 20, 1973.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a process for the production of organicsulfonic acid oligomers and to the novel compositions produced in theprocess, particularly sulfonic acid oligomers from straight chainprecursor compounds.

2. Description of the Prior Art

It is known to prepare organic sulfonic acids by the reaction of sulfurtrioxide with mono-olefinic hydrocarbons in the liquid phase at atemperature below about 100°C., usually below about 50°C., by eithercontacting the olefin with attenuated sulfur trioxide, that is withgaseous sulfur trioxide which has been diluted with a relatively inertgas, usually air, or with sulfur trioxide which is modified bycomplexing with an organic ether, acid, acid anhydride, a phosphateester, or the like. In general, the resulting sulfonate reaction productmixture only contains a minor amount of organic sulfonic acid, usuallyalkene sulfonic acid, and a major amount of alkane sultones. Additionalsulfonic acid can be obtained by hydrolysis of the sulfonation reactionmixture by treatment with aqueous caustic or aqueous mineral acid. Whenaqueous caustic is employed, the resulting product is a complex mixturewhich is mainly alkene sulfonate and hydroxyalkane sulfonate. Where acidis employed, the product is a mixture of alkene sulfonic acid andhydroxyalkane sulfonic acid. In the case of the caustic hydrolysate thecorresponding sulfonic acid can be obtained by acidification with strongmineral acid and extraction with a suitable organic solvent. The hydroxysulfonic acid, however, readily revert under acid conditions to sultoneswith mild heating.

The neutralized sulfonic acids obtained by the use of alpha olefins areexcellent surface active agents, and are particularly useful for theproduction of foamed well circulation fluids. However, aqueousconcentrates of these materials tend to solidify and separate into solidand liquid phase mixtures under the temperature conditions encounteredin the field.

A more direct process for the production of organic sulfonic acids isdesirable for reasons of cost.

A process for the production of organic sulfonic acids substantiallyfree of hydroxy substituents is desirable in order to avoid sultoneformation.

An aqueous organic sulfonate detergent concentrate which does notseparate into a mixture of solid and/or liquid phases or does so only atvery low temperatures is desirable for use in the foamed wellcirculation fluid art. [See, for example, copending U.S. applicationSer. No. 704,832, filed Feb. 12, 1968, now U.S. Pat. No. 3,463,231,issued Aug. 26, 1969. ]

SUMMARY OF THE INVENTION

It has now been found that an organic sulfonic acid oligomer mixture canbe prepared by heating in the liquid phase a feed containing one or morecompounds having a carbon atom content in the range from about 5 to 1000carbon atoms of the types and formulas:

a. sultones, ##EQU1## b. hydroxysulfonic acids, R² (--SO₃ H)(--OH) c.unsaturated sulfonic acids, R[R² (--CH=CH--)]--SO₃ H

in which R is hydrogen or a monovalent hydrocarbon radical, and R² is adivalent hydrocarbon radical, and in which the R and R² groups containno nonaromatic carbon-carbon double- or triple-bond unsaturation. Theheating is continued for a period of time sufficient for at least asignificant conversion of the feed, a period which is usually in therange from about 1 minute to 25 hours.

Surprisingly, when the feed is heated above about 110°C. in thesubstantial absence of water, i.e., where the water content of theheated mixture is less than about 5-10 percent by weight, theoligomerization reaction, a dimerization and/or intercondensation,occurs which results in the production of a mixture of molecular specieshaving an average molecular weight which is approximately double thatthe original feed. The resulting oligomer product appears to be mainly amixture of novel disulfonic acids of the formula

    (HR).sub.2 Y(RSO.sub.3 H).sub.2

in which the several R groups are the same or different alkanediylradicals and Y is a radical of the group 1,1,2,2-ethanetetrayl,1,2,4,5-benzenetetrayl, or 1,2,4,5-cyclohexanetetrayl. The total numberof carbon atoms contained by these disulfonic acid oligomers is equal tothe sum of the carbon atom contents of the two precursor monomersparticipating in the oligomerization reaction. Structuralrepresentations of the foregoing oligomers include the following:##SPC1##

i.e., including head-to-head and head-to-tail oligomerization of themonomers.

In view of the difunctionality of the subject oligomers, they areparticularly useful for the production of linear polymers, particularlythose obtainable from the disulfonyl halide derivatives of the subjectoligomers, for example:

1. R(SO₂ Cl)₂ + H₂ N(CH₂)₆ NH₂ → polysulfonamide polymer. Otherpolyfunctional comonomers, such as organic diols, polyols, etc., mayalso be employed for the preparation of useful polymers and resins fromthe oligomeric polysulfonates of the instant invention.

DESCRIPTION OF THE INVENTION

In a preferred embodiment of the present invention a mixture ofoligomerizable compound is used, namely the crude reaction productmixture resulting from sulfonating an n-alkene, for example1-hexadecene, with vaporized sulfur trioxide which has been diluted withair. When the conversion of the olefin to sulfonate is substantiallycomplete (requires about 1.20 mols of SO₃ per mol of olefin), theproduct mixture is heated to 155°-160°C. and maintained at thistemperature for 1-1.5 hours. Infrared and/or nuclear magnetic resonance(NMR) spectra analyses demonstrate that the resulting mixture containslittle or no hexadecene sulfonic acid, hydroxyhexadecane sulfonic acidor hexadecane sultone, the foregoing being the principal components ofthe sulfonated hexadecene feed.

Molecular weight and other characterizing determinations demonstrate:

1. that the product has a molecular weight corresponding to a C₃₂-disulfonic acid;

2. the product is a molecular mixture of which about 15 mol percentcontains a benzene ring, another substantial fraction contains acyclohexane ring, and a third substantial fraction is a carbon-carbonbond-bridged hexadecyl dimer containing no unsaturation; and

3. the oligomeric disulfonic acid mixture per se is a useful foamingagent as are likewise the water soluble salts of the acid.

In view of the nature of the product composition, it is clear that anumber of chemical reactions are occurring in the present process(including dimerization by reaction between two like monomers),intercondensation (reaction between dissimilar monomers, i.e.,homologs), acyclic cyclization, aromatization and intra moleculartransfer of hydrogen.

The temperature required to effect the oligomerization of the process isin the range above about 110°C. As the temperature is increased, thereaction rate becomes faster. Preferred temperatures are in the range120° -220°C. Higher temperatures may be employed advantageously providedthat carbonization and degradation of the feed does not become aproblem, a matter which varies depending upon the particular feed andusually occurs appreciably in the range 250°-300°C.

The course and degree of completion of the present oligomerizationreaction is conveniently followed by spectral analysis methods,particularly nuclear magnetic resonance (NMR) spectra of particularhydrogen atoms of the feed and product mixture. In the course of thereaction the following functional groups are eliminated from theproduct: (1) the sultone groups, (2) the carbon-carbon olefinic doublebond unsaturation, and (3) the alkanol hydroxy groups; thus theadsorption arising from: (1) protons alpha to the sultone C--O bond(usually in the range 4.4-4.6 ppm), (2) vinyl protons (usually in therange 5.0-5.9 ppm), and (3) protons alpha to the C--O bond of alkanolgroups (usually in the range 3.4-3.7 ppm) decrease as the reactionproceeds and approach or become zero when conversion is complete.Similarly, characteristic adsorptions of the aformentioned functionalgroups of the feed and product mixtures in the infrared spectrum mayalso be conveniently employed to follow the conversion. Thus, the1,3-sultones absorb significantly at 1330-1350, 1190, 1155, 1000, 940,815-880 and 620 cm.sup.⁻¹. The 1-4 sultones absorb significantly at1330-1360, 1160, 895, 810-825 and 530 cm.sup.⁻¹. Vinyl unsaturatedsulfonic acids adsorb significantly at 1700, 1165, 1040, 965 and 910cm.sup.⁻¹. The degree of conversion of the feed is convenientlyapproximated by comparing the before and after spectra of the feed andproduct using one or more of the abovenoted characteristic adsorbances.For example, the ratio of the areas under the NMR spectral curves asfollows: ##EQU2## is a measure of the unconverted feed. Conversely, asused herein, when the foregoing ratio has decreased to less than 0.90 to1, then by definition a significant conversion of feed to oligomerproduct has occurred. Similar comparisons may be used employing theother characteristics adsorbances noted above.

In addition to the foregoing characteristic spectral adsorbances, asnoted above, disulfonic acids containing benzene rings and cyclohexanerings are produced in the subject reaction. This results in new oradditional characteristic spectral adsorbances arising, for example,from hydrogen attached to a carbon atom which is a part of a benzenenucleus. These adsorbances, particularly in the NMR spectra, may also beemployed to mark the degree of completion of the process.

By oligomerization, as used herein, is meant dimerization of likemonomers and intercondensation of unlike monomers.

By longest straight chain of the compound, as used herein, is meant thedetermination as in conventional practice which is employed in thenaming of organic compounds.

The length of time required for conversion of the feed to oligomervaries depending upon the monomer or monomeric mixture employed and thetemperature of the heating. For example, using an n-C₁₅ ₋₁₈ alpha olefinsulfonation product feed, the following representative time-temperaturerelationship was noted:

                              Completion,                                         Temp. °C.                                                                          Time, Hrs.    % of Theory                                         ______________________________________                                        100         28            0                                                   120         28            91                                                  140         4             87                                                  160         1             85                                                  170         0.3           est.˜85                                       ______________________________________                                    

Thus, in view of the foregoing, the time required for substantiallycomplete conversion (90 percent plus), in general, will be in the rangefrom about 0.1 to 30-50 hours and for the preferred temperature range,140° to 179°-200°C., in the range from about 0.1 to 5 hours. Wherepartial conversions are desired, relatively shorter reaction periods areemployed.

An induction period for the oligomerization which varies depending uponthe particular feed is especially notable at reaction temperatures inthe range below about 130°-155°C. Thus at 120°C. this period may be asmuch as 1-2 hours. As this temperature is raised, the induction periodbecomes shorter and above about 160°C. is scarcely, if at all,appreciable. The use of the aforedescribed spectral analysis techniqueas a means of following the course of the reaction disposes of anyambiguity which might arise in view of the induction phenomenon.

Usually the process of the invention is effected more advantageously inthe absence of inert diluents, for example saturated hydrocarbons ormixtures thereof, but these may be employed to advantage, for examplewhere heat exchange or temperature control is a problem.

Strong mineral acid appears to promote the instant oligomerizationreaction, particularly in the case of the sultone feed compounds. In thecase of the preferred sulfur trioxideolefin reaction mixture feeds, from1-5 weight percent of sulfuric acid is ordinarily present and thepresence of additional mineral acid does not appear to improve the rateof the reaction. However, the crude oligomerization reaction productmixtures ordinarily are quite dark colored and the presence ofphosphoric acid in the heated mixture usually reduces the color.Sulfuric acid is preferred.

A wide variety of bifunctional organic compounds are suitable alone orin admixture as feeds for the present oligomerization reaction. Theymust contain at least about 5 non-aromatic carbon atoms per molecule, asulfonate functional group, i.e., --SO₃ --, and one of the following:(1) a carbon-carbon double-bond, i.e., --CH--CH--; (2) an alkanol hyroxygroup, or a sulfonate ester group of which the above sulfonate group isa component, i.e., a sultone, and the functional groups must besubstituents attached to non-aromatic carbon atoms with the balancebeing carbon and/or hydrogen. For practical purposes, the feed compoundswill usually contain less than about 1000 carbon atoms per molecule, andpreferably less than about 50. More preferably the feed compounds havestraight chain carbon skeletons and a carbon atom content in the range 5to 30.

Representative classes of compounds suitable for use as feeds for thesubject process include sultones, R² (OSO₂); hydroxy sulfonic acids, R²(--OH)(--SO₃ H); and unsaturated sulfonic acids, R[R² (--CH=CH--)](--SO₃H) in which R is hydrogen or a monovalent hydrocarbon radical and R² isa divalent hydrocarbon radical, the feed compound(s) having a carbonatom content in the range from about 5 to 1000 and containing nonon-aromatic carbon-carbon double or carbon-carbon triple bondunsaturation, and mixtures thereof. Preferred representative classes offeeds for the process herein are of the formulas ##EQU3## in which x isin the range 0-3, inclusive, and y is in the range 0-n, with n being anumber which is 4 less than the number of carbon atoms in the longeststraight chain of the compound which contains the --SO₃ H group as asubstituent, and in which the R groups may be the same or different andare hydrogen or an alkyl group. Mixtures of these classes and/orhomologs are suitable feeds.

Preferred process feeds for use herein, for reasons of cost andavailability, are the crude reaction product mixtures obtained by thesulfonation of a mono-olefinic hydrocarbon feed using sulfur trioxide asknown in the art [cf. U.S. Pat. Nos. 2,061,617; 2,094,451; 2,572,605;3,444,191, etc., as well as Ind. and Eng. Prod. Research & Development,Volume 2, No. 3, Pp. 229- 231 (1963)]. Briefly, in sulfur trioxidesulfonations the liquid olefin, either neat or dissolved in an inertmedium, is contacted with from about 0.5 to 1.5, usually from about 0.8to 1.3, mols of sulfur trioxide. The sulfur trioxide is added in avariety of ways:

1. vaporized and diluted with an inert gas, usually air;

2. complexed with an organic compound, for example dioxane, acetic acidor anhydride, etc.; or

3. as a solute in an inert medium, for example, liquid sulfur dioxide,hexane, etc.

Since the olefin sulfonation reaction is exothermic, the reactionmixture temperature is generally maintained below about 65°C., usuallybelow 50°C., by a cooling means. Somewhat higher local temperatures (ashigh as 150°C.) usually prevail briefly at the zone of initialcontacting of the reactants where air-sulfur trioxide sulfonationmixtures are employed. In these reactions, mono-olefinic hydrocarbonscontaining at least one allylic hydrogen, i.e., ##EQU4## are in generalsulfonatable by the use of sulfur trioxide and although actual crude orprocessed product mixtures vary depending upon the particularcombination of process variable employed, the product is in general asatisfactory feed for the instant oligomerization process provided thatthe water content of the feed is less than 5-10 weight per cent. Excesswater, if present, can be readily removed by conventional drying means.

Representative feeds satisfactory for use in the present oligomerizationprocess include the sulfur trioxide-olefin sulfonates derived fromsulfonatable mono-olefinic hydrocarbons such as hexadecene-1,heptadecene-2, octadecene-3, hexene-1, ethylene-growth olefins, crackedwax alpha-olefins of the C₅ -C₂₀ molecular range and fractions thereof;olefins obtained by dehydrohalogenation of hydrocarbon halides; internalolefins obtained by partial or complete double-bond isomerization, i.e.,partial or complete equilibration; pentacontene, tetracontene,triacontene, eicosene; substituted olefins such as 9-methyldecene-1,8-cyclohexylundecene-2, 10-phenyldecene-3,7,8,9,10-tetramethylundecene-1, 19-methyleicosene, 19-ethyleicosene-5,4-isopropylpentadecene-1, 7-methyloctene-1; dimers and trimers(oligomers) of lower substantially straight chain olefins such as2-butyloctene-1, 2-hexyldecene-1; and the like mono-olefinichydrocarbons.

Representative unsaturated hydrocarbon sulfonic acids suitable for useherein include hexadecene sulfonic (all isomers singly or in admixture),n-C₆ -C₂₀ -alkene sulfonic (molecular mixtures, fractions thereof and/orisomeric mixtures), n-hexene sulfonic, 11-methyl-1-sulfonic-dodecene-3,6-cyclohexyl-1-sulfonic-hexene-2, 6-phenyl-1-sulfonic-heptene-4,eicosene sulfonic, pentacontene sulfonic, and the like acids.

Representative hydroxyalkane sulfonic acids suitable for use hereininclude 4-hydroxyoctadecane 1-sulfonic acid, 5-hydroxyoctane-3-sulfonicacid, 19-methyl-4-hydroxyeicosane-1-sulfonic acid,7,8,9,10-tetramethyl-5-hydroxyundecane-2-sulfonic acid,6-cyclohexyl-4-hydroxy-heptane-1-sulfonic acid, 9-hydroxydecane-1sulfonic acid, 4-isopropyl-3-hydroxypentadecane-1-sulfonic acid,16-phenyl-3-hydroxyheptadecane-2-sulfonic acid,5-hydroxypentacontane-1-sulfonic acid, 4-hydroxy-tetracontane-2-sulfonicacid, 3-hydroxytriacontane-1-sulfonic acid;18-hydroxyeicosane-2-sulfonic acid, 4-hydroxycyclohexane-1-sulfonicacid, and the like hydroxy-sulfonic acids.

Representative suitable feeds for use herein include sultones of thecorresponding hydroxysulfonic acids, i.e., beta-, gamma-, delta- andepsilon-sultones of 2-, 3-, 4-, and 5-hydroxy-alkane sulfonic acids suchas 2-hydroxyoctadecane-1-sulfonic, 6-hydroxyeicosane-2-sulfonic,6-hydroxy-11-phenyl-heptadecane-3-sulfonic, 5-hydroxyhexane-1-sulfonic,3-hydroxynonadecane-1-sulfonic,4-hydroxy-11-methyltetradecane-8-sulfonic,3-hydroxyoctadecane-1-sulfonic, 4-hydroxypentadecane-2-sulfonic,4-hydroxytridecane-1-sulfonic, 3-hydroxynonane-1-sulfonic,9-cyclohexyl-4-hydroxydecane-1-sulfonic,4-hydroxypentacontane-1-sulfonic, 10-phenyl-3-hydroxydecane-6-sulfonic,8-isopropyl-4-hydroxyhexadecane-1-sulfonic,4-hydroxycyclohexane-1-sulfonic, and the like acids.

EXAMPLES

The following examples further illustrate the invention.

EXAMPLE 1

Sulfonation of 1-Hexadecene

Th sulfonation unit consisted of a 5 mm. I.D. 3 foot, jacketed fallingfilm reactor equipped with an inlet weir for the olefin feed, a central3 mm. O.D. sulfur trioxide-air inlet tube, followed by a 13/8 by 4 inchpost reactor tube. This reactor was continuously charged with1-hexadecene at a rate of 4.36 grams/min. Simultaneously there was added1.87 grams/min. of SO₃ diluted to 5% by weight in air (an olefin/SO₃ molratio of 1.2/l). The temperature of the outer surface of the reactorwall was maintained in the range of 45° to 65°C. by circulating coolingwater in the jacket. The sulfonation product was collected and chilledto 0°C. over a period of 2 hours. The product weighed 739 grams.

The infra-red (IR) spectrum of this reaction product showed the presenceof both sultone and sulfonic acid. The 1,3-sultone absorbs at 1330-1350,1190, 1155, 1000, 940, 815-880, and 620 cm.sup.⁻¹. The 1,4-sultoneabsorbs at 1330-1360, 1160, 895, 810-825, and 530 cm.sup.⁻¹. Unsaturatedsulfonic acid absorbs at 1700, 1165, 1040, 965 and 910 cm.sup.⁻¹. Theabove peaks were present

The NMR spectrum also showed that the product was a mixture of sultonesand unsaturated sulfonic acids. Protons beta to sulfonate in thesultones absorb at 2.1-2.6 ppm.; those alpha to sulfonate in thesultones absorb at 2.8-3.2 ppm.; the proton alpha to the sultone C--Obond absorbs at 4.4-4.6 ppm.; vinyl protons absorb at 5.0-5.9 ppm. Allthese peaks were present.

A 10 g. portion of the crude acid/sultone product was analyzed by coldneutralization (room temperature) with 13 millimoles of NaOH in aqueousalcohol followed by complete hydrolysis and neutralization at 95°C. Thisanalysis showed the initial presence of 34% sulfonic acid and 66%sultones. The sodium salt solution obtained was deoiled by 3 extractionswith petroleum ether from a 75% alcohol solution and found to containabout 0.5 weight per cent of oil. Thus, both the original sulfonationstep and the hydrolysis step were substantially complete. Foamfractionation indicated the presence of about 16% di- orpoly-sulfonates. The IR spectrum of this salt showed the typical bandsat 1180-1200, 1065, 795, 620 and 530 cm.sup.⁻¹ for a sulfonate salt plusa band at 965 cm.sup.⁻¹ from trans double-bonds.

EXAMPLE 2

Oligomerization of the Hexadecene-SO₃ Reaction Product

The acid reaction product from Example 1, 50 grams, was heated in around bottomed flask at 150°-153°C. for 21/4 hours. At the end of thistime, the viscosity of the heated material was considerably greater thanthat of the starting material.

An infra-red spectrum showed strong adsorption at 1700, 1165, 1040, 910cm.sup.⁻¹, all of which are typical of aliphatic sulfonic acids. Theabsence of adsorption bands at 1330-1360, 895 and 810-880 cm.sup.⁻¹showed that the sultone originally present in the feed stock had allbeen converted. The absence of a 965 cm.sup.⁻¹ adsorption band showedthat there were no 1,2-disubstituted double bonds, i.e., allalkene-sulfonic acid was converted.

A nuclear magnetic resonance (NMR) spectrum had adsorption at 2.9-3.2ppm, typical of aliphatic sulfonic acids. The absence of any bonds at4.4-4.6 ppm and at 5.0-5.9 ppm also indicated complete conversion of thesultone and the absence of any 1,2-disubstituted double bonds,respectively.

A neutralization equivalent analysis required 0.0032 mols of base pergram of product.

The product was shown to have 2.3% water by a Karl Fisher titration.

The remainder of the product was converted to the sodium salt and wasthen desalted by precipitation from 70% aqueous ethanol and deoiled by 5extractions of this solution with petroleum ether. The precipitate wasanalyzed for Na₂ SO₀₃₉₀ 4 and the extract was concentrated. Thisprocedure showed the presence of 1.5% (wt.) oil and 0.4% sodium sulfatein the reaction mixture. The I.R. spectrum of the sulfonate salt wastypical of the IR spectrum of olefin sulfonate salts, except there wasno adsorption at 965 cm.sup.⁻¹, i.e., there were no double bonds of thetrans configuration.

EXAMPLE 3

Esterification of the Oligomerization Product of Example 2

A portion of the product of Example 2, 5.00 grams, was dissolved inabout 250 ml of diethyl ether. Then diazomethane formed by thedecomposition of N-methyl-N-nitroso-p-toluene-sulfonamide 8 Reference:Rec. Trav. Chem. 73, 229 (1954)] was bubbled into the ether solutionuntil the solution had a persistent yellow color. This solution wasfiltered to give 0.08 grams of an insoluble residue. Then the ether wasremoved from the filtrate by evaporation to give 5.26 grams of a viscousbrown liquid. Infra-red and NMR analyses were run on this ester. Theinfra-red spectrum showed adsorption bands at 1360, 1170, and 995cm.sup.⁻¹, all of which are characteristic of methyl aliphatic sulfonateesters. There were no noticeable adsorptions characteristic of sultoneor of trans olefinic double bonds in the ester. There were no hydroxyladsorption bands at 3200-3700 cm.sup.⁻¹. There were no ether adsorptionbands at 1060-1150 cm.sup.⁻¹.

The molecular weight of the oligomer ester was found to be 627 by thethermoelectric measurement of vapor pressure (Reference: ASTM D2503-67), and the highest mass peak obtained from a mass spectralanalysis was 638 mass units.

EXAMPLE 4

Preparation and Separation of SO₃ -Hexadecene Sulfonation Product

A 1-hexadecene-SO₃ reaction product was prepared as in Example 1 exceptthat less SO₃ (1.20 g/min.) was used, resulting in an SO₃ /olefin moleratio of 0.77/1. The product was collected in about 4 volumes ofn-pentane. As in Example 1, a portion of this product was analyzed byneutralization, hydrolysis, desalting, deoiling and foam fractionationto show that the original sulfonation product contained about 50%sultone, 24% sulfonic acid, 1% disulfonate, and 25 mole % unreactedolefin.

Another portion (50 ml.) of the above pentane solution was filtered atroom temperature to recover 0.66 g. of crystallinehexadecane-1,3-sultone, and then cooled in an ice bath and refiltered torecover another 1.00 g. of hexadecane-1,3-sultone. The remaining pentanefiltrate was mixed with 21 ml. H₂ O and 75 ml. acetone and extractedfive times with n-pentane to give another 4.0 g. of sultone (mixed with2.4 g. unreacted olefin). The sultone fractions were combined.

The aqueous-acetone layer which contained the sulfonic acid fraction ofthe product was stripped of solvents at 40°-45°C. under a vacuum to give2.85 g. of viscous acid identified as hexadecane sulfonic acid on thebasis of an IR spectrum which showed the presence of trans olefinicdouble bond (965 cm.sup.⁻¹) and the absence of sultones (no 830 and 530cm.sup.⁻¹ bands).

EXAMPLE 5

Dimerization of Hexadecene Sulfonic Acid

The sulfonic acid prepared in Example 4 (1.42 g) was heated at 160°C.for 2 hours. The reaction product had IR and NMR spectra, which for allpractical purposes was identical to that of the acid product of Example2.

EXAMPLE 6

Dimerization of Hexadecane-1,3-Sultone

Hexadecane-1,3-sultone (10 g, twice recrystallized from petroleum ether)was heated for two hours at 157°-187°C. The IR and NMR spectra wereessentially identical to that of the acid product of Example 2. Theoligomeric acid was methylated as in Example 3. Carbon-hydrogen analyseson the methyl ester were 63.58% C, 10.52% H. Theoretical for C₃₄ H₆₈ S₂O₆ is 64.10% C, 10.76% H.

The NMR spectrum of the methyl ester showed adsorption at 6.6-7.0 ppmcorresponding to the presence of substantial amounts of hydrogen atomsbonded to aromatic ring carbon atoms. Assuming a tetrasubstitutedaromatic ring, this corresponds to about 15 mol per cent of the product;similar adsorptions were observed in the NMR spectra of the products ofExample 2, 3 and 5.

EXAMPLE 7

Oligomerization of SO₃ -Octene-1 Sulfonate

Example 1, 2 and 3 were repeated except that the 1-olefin used was1-octene and the sulfonation mole ratio was 0.25 moles SO₃ per mole ofolefin. The excess octene was removed from the sulfonation product undervacuum a 40°-45°C. The oligomerization was conducted for two hours at160°-164°C. IR and NMR spectra of the acid and methyl ester were thesame as obtained for the 1-hexadecene product except for the effect ofthe shorter alkyl chain. The vapor pressure molecular weight value ofthe methyl ester was 471; the major mass spectral peaks ran up to 414.

EXAMPLE 8

Effect of the Excess Water on the Oligomerization

Fifty grams of the unneutralized acid product of Example 1 was placed ina Fischer-Porter bottle equipped with a magnetic stirrer along with 10grams of water. The mixture was heated to 150°C. and stirred at thistemperature for 6 hours. At the end of this time cold neutralizationwith NaOH required 3.08 millimols/g. Deoiling as before showed thatsulfonic acid had been formed and that only 10% of the original sultoneremained. In this case, in contrast to Example 2, the material had notbeen oligomerized, but had been simply hydrolyzed to alkene- andhydroxyalkane-sulfonic acid. Both the acid and the sodium salt showedsubstantial 965 cm.sup.⁻¹ peaks in the IR spectrum. Analyticalhydrogenation of the salt showed the presence of about 67%alkene-sulfonate. The presence of hydroxyl groups was demonstrated byconverting the hydroxy-alkane acid component back to sultone as follows.The water was removed by vacuum from a 2.01 g. sample of the abovehydrolyzed acidic product, followed by heating at 100°C. for 1 hour.Cold neutralization of this product gave a neutralization equivalent of2.47 millimoles/gram or a decrease of 31% compared with the hydrolyzedacid on a dry basis.

EXAMPLE 9

Conversion of Normal Olefin Sulfonate to Methyl Ester

A 19 g. sample of normal neutralized and hydrolyzed 1-hexadecenesulfonate, as described in Example 1, in aqueous solution (25%) wassubjected to the ether-HCl extraction procedure [Reference: R. House andJ. L. Darragh, Anal. Chem. 26, 1492 (1954)] to convert it to thecorresponding sulfonic acid dissolved in ether. The ether solution wasmethylated as in Example 3 to form 17.25 g. of clear, yellow oil whoseIR spectrum showed substantial hydroxyl adsorption at 3200-3600cm.sup.⁻¹, and large bands at 1350, 1170 and 995 cm.sup.⁻¹.

EXAMPLE 10

Plasticization of Polyvinyl Chloride

The methyl esters of Examples 3 and 9 were mixed in a 60/40/1 ratio witha commercial polyvinyl chloride resin/ester/commercial stabilizer andpressed into sheets at 182°C. Both materials plasticized the resin.Physical properties of the plastic sheets were as follows:

                                VOLATILITY, % at                                                     COMPATIBILITY                                                                          200°F. - 66 HRS.                           __________________________________________________________________________    Example 3, Oligomer Ester                                                                        Fair     6.3                                               Commercial Dioctyl Phthalate                                                                     Standard 10.5                                              Example 9, Olefin Sulfonate Ester                                                                Poor     16.3                                              __________________________________________________________________________

These data indicate that the SO₃ -olefin sulfonate oligomer products areuseful plasticizers for polyvinyl chloride resins.

EXAMPLE 11

Preparation of Mixed Olefin-SO₃ Reaction Mixture

The reactor used for this sulfonation consisted of a continuous fallingfilm-type unit in the form of a vertical water-jacketed tube. Both theolefin and the SO₃ -air mixture were introduced at the top of thereactor and flowed concurrently down the reactor. At the bottom thesulfonated product was separated from the air stream.

The olefin feed was a straight-chain 1-olefin blend produced by crackinghighly paraffinic wax and having the following composition by weight: 1%tetradecene, 27% pentadecene, 29% hexadecene, 28% heptadecene, 14%octadecene and 1% nonadecene. This mixture was charged to the top of theabove described reactor at a rate of 306 pounds/hour. At the same time124.2 pounds/hour of SO₃ diluted with air to 3% by volume concentrationof SO₃ was introduced into the top of the reactor. The reactor wascooled with water to maintain the temperature of the effluent productwithin the range of 43°-46°C. The average residence time of thereactants in the reactor was less than 2 minutes.

After passing out the sulfonation reactor the sulfonated product wasmixed with 612 pounds/hour or 11.2% aqueous caustic and heated to145°-150°C. in a tubular reactor at an average residence time of 30minutes in order to hydrolyze and neutralize the sulfonated product.Olefin sulfonates were produced at the rate of 463 pounds per hour as anaqueous solution having a 45% by weight solids content and a pH of 10.8.

A portion of this product was analyzed and shown to be made up of thesodium salts of alkene sulfonic acids, hydroxyalkane sulfonic acids, anddisulfonic acids. These three major components were present in a weightratio of about 50/35/15, respectively.

After operating in the above-described manner for several hours, theneutralization and hydrolysis vessels were replaced by a collectingtank, and the acid reaction product was collected for use as a feed forthe oligomerization reaction.

EXAMPLE 12

Oligomerization of n-C₁₄ C₁₉ Mixed Olefin-SO₃ Sulfonate

The acid product from Example 11 was heated at 150° to 155°C. for 3hours. At the end of this time an infra-red analysis indicated thatessentially all sultone and alkene sulfonic acid had been converted tooligomeric acids. This reaction mixture was neutralized to a pH of 7 to8 using 8% aqueous caustic. The resulting solution was dried to give thesodium salt which contained only about 7% non-surface active material asmeasured by a cationic titration.

EXAMPLE 13

Foam Stability of the Oligomeric Sulfonic Acid Salts and MixturesThereof

The neutralized reaction product from Example 12, 43 parts, wasdissolved in 57 parts of a 2/1 mixture of water and isopropyl alcohol.One-half gram of the resulting test solution was dissolved in 100 ml ofwater in a 600 ml graduated beaker. The solution was stirred rapidly for1 minute with an efficient stirrer. This procedure converted essentiallyall of the liquid into foam. The maximum volume of foam and the timerequired for 50 ml of liquid to drain from the foam were measured (RunNo. 1). The same experiment was also carried out on a mixture consistingof 24 parts of the neutralized product of Example 12 and 16 parts of theneutralized monosulfonate prepared in Example 11 (Run No. 2) dissolvedin 60 parts of the water isopropanol solvent. Two other experiments(Runs 3 and 4) were carried out using 1 gram portions of the two testsolutions dissolved in 100 ml of water. The same four experiments werethen carried out with 10 ml of added kerosene. The results are given inthe following table:TEST SOLUTION WITHOUT KEROSENE WITHKEROSENE__________________________________________________________________________Time Time Initial for 50% Initial for 50% Gms/100 M1 Foam Drain FoamDrainRun No. Water Composition (M1) (Min.) (M1)(Min.)__________________________________________________________________________10.5 Oligomer 400 3-1/6 375 3-1/3 Sulfonate2 0.5 Oligomer 400 3-5/6 4004-5/6 Sulfonate/ Monosulfonate3 1.0 Oligomer 450 3-1/3 450 4-1/3Sulfonate4 1.0 Oligomer 475 4-1/6 500 5-1/3 Sulfonate/Monosulfonate__________________________________________________________________________

These data demonstrate that olefin sulfonate oligomers are excellentfoaming agents, being particularly suitable for use in the preparationof foamed oil well circulation fluids. The oligomer-monomer sulfonatemixtures moreover, yield even better foamed well circulation fluids.

EXAMPLE 14

Effect of Water on Oligomerization Reaction

Stainless steel tubes having a capacity of 15 ml were charged with 10grams of a test solution made up of the olefin/SO₃ reaction mixture fromExample 11 and water. The tubes were sealed and inserted horizontallyinto a large metal block maintained at a temperature of 150°C. Theentire block with the enclosed tubes was shaken at a rate of 150 cyclesper minute, for 2 hours. Then the tubes were quenched by immersion intocold water.

The contents of each tube were removed and checked for appearance andviscosity. A weighed portion of each test mixture, about 0.4-0.45 grams,was dissolved in 50 ml of ethanol and neutralized with 0.1 n NaOH. Theresulting solution was then diluted to 100 ml with water and examinedfor solubility. The increasing presence of unconverted, neutral, waterinsoluble alkane sultone was observed as the water content presentduring oligomerization increased:

    TEST SOLUTION REACTION PRODUCT                                                __________________________________________________________________________                           Appearance of                                          Reaction Mix.                                                                          H.sub.2 O     Sodium Salt in                                         (Grams)  (Grams)                                                                            Viscosity                                                                              50% Aq. Ethanol                                        __________________________________________________________________________    10       0    Most Viscous                                                                           Clear                                                  9.9      0.1  Less Viscous                                                                           Slight Haze                                            9.7      0.3  Least Viscous                                                                          Cloudy                                                 9.5      0.5  Semi-Solid                                                                             Separate Insol. Layer                                  9.3      0.7  Semi-Solid                                                                             Separate Insol. Layer                                  9.0      1.0  Semi-Solid                                                                             Separate Insol. Layer                                  __________________________________________________________________________

EXAMPLE 15

Effect of Temperature on Oligomerization Reaction

A 500 ml 3-inch round bottom flask, equipped with a paddle stirrer, anitrogen inlet, thermometer and gas outlet tube was heated to about5°-10°C. above the desired temperature. Nitrogen gas was passed slowlythrough the flask. Then an olefin/SO₃ reaction mixture made as inExample 11 and weighing about 200 grams, was charged to the flask. Thereaction mixture was stirred with nitrogen flowing over the surface.Samples were removed periodically and cooled to room temperature.

Each sample was checked for color and viscosity, and an 0.4 to 0.5 gramsample was titrated with 0.1 NaOH to determine the acid content. Anothersmall portion was titrated for anionic surface active components with astandard cationic surfactant.

The extent of reaction at various times was determined for runs at fourtemperatures:

             Time to 25%     Time to 75%                                          Temp. °C.                                                                       Conversion (Hrs.)                                                                             Conversion (Hrs.)                                    ______________________________________                                        120      5.5             10.0                                                 140      0.8             1.4                                                  160      --              0.4                                                  ______________________________________                                    

These data demonstrate that temperature effects in the oligomerizationherein are the usual time-temperature relationship, i.e., roughly adoubling of reaction rate occurs for each 10°C. increase in reactiontemperature.

EXAMPLES 16-22

A series of sultones were prepared and oligomerized by heating at 170°C.for 4 hours in the apparatus of Example 14. The neutral, and freesultones were recovered from the crude reaction product of theair-diluted sulfur trioxide sulfonation of the olefins, decene-1,dodecene-1, tetradecene-1, hexadecene-1, octadecene-1, eicosene-1 anddocosene-1. The extraction technique employed for the separation of thesultones was as described in Example 4. In each case theoligomerizations were substantially completed in the 4 hour reactionperiod.

EXAMPLES 23-27

Oligomers as Built Detergents

The surface active nature of the present oligomers, particularly the C₂₈-C₄₀ -disulfonates, i.e., oligomers of the C₁₄ -C₂₀ sultones, in builtdetergent formulations was demonstrated as follows. Representativeoligomers obtained in Examples 6 and 16-22 were each neutralized withaqueous caustic and then evaporated to dryness to give the correspondingsolid sodium salts. These salts were each compounded into a detergentformulation having the following composition in parts by weight: 25parts of the sodium salt of the polysulfonic acid, 7 parts sodiumsilicate, 1 part carboxy methyl cellulose, 8 parts water, and 59 partssodium sulfate. The resulting compositions were each dissolved in 50 ppmhard water to give an 0.1% concentration which was then tested fordetergency. In this detergency test, the soil removal efficiency of atest material is related to that of a good and a bad standard. The goodstandard is arbitrarily assigned a detergency rating of 6 and the poorstandard a rating of 2. Then the test materials are given values on thesame scale according to their relative detergencies compared to thestandards. The results of this detergency test are given in thefollowing table:

    Example                                                                       No.    Active Component Relative Detergency                                   ______________________________________                                        23     C.sub.10 -Sultone Oligomer                                                                     2.2                                                   24     C.sub.12 -Sultone Oligomer                                                                     2.3                                                   25     C.sub.14 -Sultone Oligomer                                                                     4.3                                                   26     C.sub.16 -Sultone Oligomer                                                                     4.0                                                   27     C.sub.18 -Sultone Oligomer                                                                     4.6                                                   ______________________________________                                    

These data demonstrate that the subject sulfonate oligomers andparticularly those of the C₁₄ to about C₃₀ sultones, hydroxyalkanesulfonic acids and the alkene sulfonic acids or mixtures thereof areuseful built detergents. Individual molecular weight, i.e., C-numberspecies and mixtures or fractions of the C₁₀ -C₃₀ -oligomers are alsouseful. Other builders such as sulfate salts, phosphate builders andphosphate-free builders, as known in the art, are also suitable for thecompounding of built detergents with the present novel oligomericsulfonic acid salts (i.e., the usual water soluble alkaline salts suchas the alkali metal salts, e.g., sodium and potassium; the ammoniumsalts the calcium and magnesium salts and the like, as known in thedeterge art). The unneutralized oligomers herein, i.e., the disulfonicacids per se are useful as the foaming agent for the production ofpreformed acidic well circulation fluids, particularly in the oil wellservicing art.

EXAMPLES 28-34

In the use of foaming agents for the prepartion of foamed wellcirculation fluids liquid concentrates of the surface active agent areordinarily employed provided that phase separations, particularly solidformations, do not occur upon standing or at the low temperatures oftenencountered at the wellhead in the field. These examples demonstratethat liquid concentrates of mixtures of the subject oligomers with theprecursor monomer or of the oligomers per se are useful foaming agentshaving excellent low temperature characteristics. The olefin sulfonatemonomer used in these examples was the C₁₄ -C₁₉ -product obtained bybase hydrolysis of the product described in Example 11. The oligomerused was the product obtained as described in Example 12. The liquidconcentrates tested contained 40 parts (weight) water, 20 partsisopropanol and 40 parts of the active, as noted in the table below.These concentrates were cooled to 0°C. with the results as also noted inthe table below.

    ______________________________________                                        Example Oligomer-Monomer                                                      No.     Weight Ratio   Observation                                            ______________________________________                                        28       0/100         Rapid Solidification                                   29      20/80          Rapid Solidification                                   30      30/70          Slow Solidification                                    31      40/60          Slow Solidification                                    32      50/50          Mostly Liquid. Some                                                           Suspended Solids                                       33      60/40          Clear Solution                                         34      100/0          Clear Solution                                         ______________________________________                                    

When other lower alcohols (i.e., alcohols having less than 4 carbonatoms) such as methanol, ethanol, n-propanol and mixtures thereof areused as the cosolvent, similar results are obtainable.

The foregoing examples demonstrate that the subject disulfonateoligomers per se yield liquid detergent concentrates having excellentlow temperature characteristics, e.g., solubility etc. Similarly, thesedata demonstrate that the subject oligomeric disulfonates are useful asadditives for the improvement of the low temperature characteristics ofsulfonate detergent actives whose liquid concentrates have poor lowtemperature solubilities.

We claim:
 1. In the method of circulating a gas-in-liquid foam in a wellthe improvement which comprises generating said foam from a gas and afoamable aqueous solution containing as foaming agent the oligomerobtained by the process which comprises heating in the liquid phase afeed comprising at least one compound having a carbon atom content of atleast 5 but less than 50 selected from the group of the formula

    a)      RCH(CH.sub.2).sub.x CHRSO.sub.2,                                              ||                                                          O                                                                     b)      RCH(OH)(CH.sub.2).sub.x CHRSO.sub.3 H, and                            c)      RCH=CH(CH.sub.2).sub.y CHRSO.sub.3 H                              

wherein x is the number 0 and integers 1-3 and y is a whole number inthe range 0-n wherein n is a number which is 4 less than the number ofcarbon atoms in the longest straight chain of the compound containingthe --SO₃ H group as a substituent, and wherein the several R groups arethe same or different and are hydrogen or alkyl hydrocarbon radicals;said heating being at a temperature above about 110°C and below thecarbonization temperature of the feed, in the substantial absence ofwater, and for a period at least sufficient for a significant conversionof the feed to the corresponding oligomeric disulfonic acids andcirculating said foam in said well.
 2. The method as in claim 1 whereinsaid heating is continued until the ratio of the nuclear magneticresonance absorbance of

    [2(3.4 to 3.7 ppm + 4.4 to 4.6 ppm) + 5.0 to 5.9 ppm]

for the feed and resulting product mixture has decreased to about 0.90to 1, respectively.
 3. The method as in claim 1 wherein said temperatureis in the range from about 120° to 200°C and said feed compounds containfrom about 5 to 30 carbon atoms.
 4. The method as in claim 3 whereinsaid feed is of the sultone group.
 5. The method as in claim 3 whereinsaid feed is of the hydroxy sulfonic acid group.
 6. The method as inclaim 3 wherein said feed is of the alkene sulfonic acid group.